Social Signals

Sexual signals not so strict

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Science  13 Apr 2018:
Vol. 360, Issue 6385, pp. 167
DOI: 10.1126/science.360.6385.167-a

Bill color in waxbills changes with external temperature.


Sexual signals in animals, such as bright plumage, are thought to be predetermined or to be badges of quality that can reflect an animal's current condition. Direct and immediate effects of the environment in which an animal lives are rarely considered to shape these phenotypes. Funghi et al., however, found that in waxbills, bill color—a trait that can change quickly—is not the result of predetermined sexual differences, aggression, or sexual selection, but rather appears to be influenced by changes in the abiotic environment. Bill brightness was reduced in females after a series of lower-temperature nights. The authors suggest that this indicates that environmental conditions place constraints on these types of traits, limiting the degree to which they can reflect quality or be used for social interaction.

Behav. Ecol. Sociobiol. 10.1007/s00265-018-2486-6 (2018).

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